During well construction and other downhole operations, it is common for drill bits and other tools to become stuck. When this occurs, there are a very limited number of techniques usable to wholly or partially free or remove this expensive equipment, many of which involve cutting or otherwise perforating a tubular string to remove at least a portion of the string and any attached tools from the wellbore.
Typically, drilling equipment requires use of heavy-walled tubular members, having small inner diameters, which limits the amount of working space within a tubular string. Therefore, when cutting or otherwise attempting to remove these heavy-walled tubular components, the effectiveness of cutting and removal tools is limited due to the small size of such components necessary for insertion into the tubular string.
Tubular strings include numerous joints, used to connect lengths of drill pipe, drill collars, bits, steering devices, sensors, and other tools and tubular components. To maximize the effectiveness of a cutting device, it is desirable to position and retain a slitter or similar tool directly over a joint between tubular segments. Joints within a drilling string typically include male and female, pin and box ends, thus when cutting a tubular string at a joint, a somewhat thinner section of tubular can be cut. Additionally, cutting a tubular string at a torqued joint releases the tensile forces holding the tubular segments together. This reduction in tensile force at the joint allows the tubular segments to be more readily pulled apart, enabling retrieval of the upper portion of the tubular string.
When screwed together and properly torqued, joints within a tubular string become relatively seamless, thus difficult to locate using conventional devices. While casing collar locators and similar devices are usable to position a tool within a tubular string, these devices are limited in their accuracy, and are generally accurate only within a number of feet. A joint within a tubular string may be only inches in length, requiring far more precise placement of a tool than what is conventionally available using collar locators and similar devices.
Other positioning systems include providing physical features within the interior of a tubular string that interact with corresponding physical features of a locating tool, however these positioning systems require numerous precisely crafted features to ensure proper function and interaction, including various moving parts to cause selective engagement between corresponding features.
A need exists for systems and methods for positioning a tool within a tubular string that enable precise positioning of tools at a preselected location, including joints within the tubular string to facilitate the effectiveness of cutting tools.
A further need exists for systems and methods for positioning a tool within a tubular string that are simple in construction and function, able to incorporate reusable, machinable, and re-machinable parts able to accommodate a variety of latching and/or engaging orientations.
A need also exists for systems and methods for positioning a tool within a tubular string that are pre-tensioned and directionally biased, able to selectively engage and disengage from selected locations.
The present invention meets these needs.